In addition, cancer cell migration involving the CXCL12→CXCR4 axis may be caused by other cells—for example, CAFs in gastric cancer, where chronic hypoxia increases the expression of CXCL12 and thus acts on tumor cells with a hypoxia-enhanced expression of CXCR4 [212]. The gene discussed is CXCR4; the disease is neoplasm.